The present invention relates to an assembly of a fluid coupling device and a fan, and more particularly, to an improved arrangement for attaching a fan to a fluid coupling device, as well as an improved method for such attachment.
It will become apparent to those skilled in the art from the subsequent description that the mounting arrangement of the present invention may be utilized advantageously with various types of fans, as well as with various types of fluid coupling devices. However, the invention is especially useful for attaching a radiator cooling fan for cooling a vehicle engine to a viscous fan drive, and the invention will be described in connection therewith. The invention is also especially useful when the fan is of the type having a hub portion and fan blades molded integrally therewith from a plastic material. Furthermore, the invention is especially useful when the fluid coupling device is of the type in which either the body member or the cover member comprises a die-cast member, and preferably, a die-cast aluminum member.
The fluid coupling device (viscous fan drive) is now well known to those skilled in the art, an example of which is shown in U.S. Pat. No. 4,974,712, assigned to the assignee of the present invention and incorporated herein by reference. Conventionally, the fluid coupling device is manufactured separate from the fan assembly, and they are brought together for the first time at, for example, the engine assembly plant.
The typical fan assembly of the type used with a viscous fan drive comprises a stamped, sheet metal connecting member, with the fan being formed by injection molding, wherein the hub of the fan is molded around a portion of the sheet metal connecting member. Subsequently, the fan assembly is bolted to the fan drive, by means of a series of bolts. Therefore, either the cast body or the cast cover of the fan drive must include a series of tapped, internally-threaded holes to facilitate bolting of the fan assembly to the fan drive.
As a result of the conventional fan and fan drive arrangement and assembly method, there is substantial expense incurred for the extra machining (tapped holes) of either the body or the cover, as well as the cost of the bolts, and the labor cost associated with bolting the fan to the fan drive. Furthermore, the process of tapping the bolt holes in the body or in the cover has the potential of causing damage to the body or cover, resulting in a higher scrap rate than would otherwise occur, which is an additional, unnecessary expense.